Transparency in Eevee Blender 2.81 not working
In EEVEE, I find that glass shaders don't work so well, so I leave them for cycles. For EEVEE, I use this arrangement to get realistic glass - pay attention to the blend modes I have highlighted on the right. If you absolutely must use a glass shader, go with the arrangement I placed above, but generally I find the one I have highlighted (framed) works best. I tinted it blue just to show it better with the fresnel. See image: